Carbon Quantum Dot (CQD)-Based Composite Fluorescent Hydrogel for the Isolation and Determination of Iron (III)

AbstractCarbon quantum dots (CQDs) were derived from saponin and introduced into polyacrylamide hydrogel to prepare a novel bifunctional material (CQDs@HG). This hydrogel emitted strong blue fluorescence under ultraviolet light (365 nm) and exhibited stable adsorption and detection of iron(III) in water samples. The morphological characteristics, chemical composition, Fe3+ adsorption performance, and optical properties of CQDs@HG were characterized. Depending upon the Fe3+ concentration, CQDs@HG exhibited different quenching effects to allow Fe3+ determination. The limit of detection was 0.115 μM, and the adsorption was as high as 12.13 mg/g. The mechanism was due to both static and dynamic quenching. Notably, the sensor based on CQDs@HG successfully determined Fe3+ in water samples, with spiked recoveries between 95.32% and 103.11%. When combined with software image analysis, the sensor semi-quantitatively determined Fe3+ in the field. This fluorescent hydrogel provides a reference for constructing portable sensors for monitoring hazardous substances in water.Keywords: Carbon quantum dots (CQDs)fluorescent hydrogeliron(III) AcknowledgmentsWe thank Shiyanjia Lab (www.shiyanjia.com) for linguistic assistance during the preparation of this manuscript.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis research was financially supported by Project Fund of Salt Lake Chemical Engineering Research Complex, Qinghai University and the Natural Science Foundation of Qinghai (No. 2020-ZJ-702).